The present invention relates to a tracking arrangement for a moving belt and more particularly to a tracking arrangement in the form of a centering and alignment structure for a supported moving flexible fibrous filter belt or web.
Moving filter belt arrangements, particularly those filter belts of porous fibrous material utilized with various types of pressure, vacuum and ambient filter structure for filtering particulate materials have employed a number of belt tracking or centering arrangements for the moving filter belts. These past tracking arrangements which have included crowned, rounded or tapered drive and/or driven rollers have not always proven to be effective with centering problems increasing with varying belt tensions and extended belt lengths and widths.
In prior U.S. patents, two types of structures generally have been utilized to track and centrally align moving belts--namely those which have utilized band members associated with belt support rollers and those which have utilized guide shoes associated with the side edges of moveable belts. In that group of patents utilizing roller associated band members, U.S. Pat. No., 3,116,244, issued to S. S. Davis et al on Dec. 31, 1963, teaches belt centering lands integral with moveable belt support rollers, the lands extending on the roller in a fixed, helically skewed direction to opposite roller extremities; U.S. Pat. No., 3,144,409, issued to L. A. Jouhola on Aug. 11, 1964, also teaches similar lands or helical ridges formed on a discharge roller to extend to roller extremities with fluid pressure between spaced turns serving to transversely balloon a moveable support belt; U.S. Pat. No. 3,997,448, issued to E. Woodland on Dec. 14, 1976, teaches similar helices fixed to a support roller to impose a transverse bias on tension bands of a filter belt; and, finally U.S. Pat. No. 4,684,011, issued to T. C. Schneider on Aug. 4, 1987, teaches O-rings mounted on rollers with traction pressure shoes directly engaging such O-rings for effecting roller rotation. In effect, the band members of this group of aforementioned patents are functionally and structurally different from the novel and unique structural arrangement as set forth herein.
In that group of patents which utilize guide shoes, namely U.S. Pat. Nos. 3,503,517, issued to A. C. Barnebl on Mar. 30, 1970; No. 3,598,244, issued to R. E. Babcock, Jr. on Aug. 10, 1971; No. 3,615,023, issued to A. C. Barnebl on Oct. 26, 1971 and No. 3,642,142, issued to A. C. Barnebl et al on Feb. 15, 1972--each teaches belt edge gripping structure engaging along the side edges of a moveable belt to place a lateral tension thereon. This latter group of patents--like the aforediscussed band member patents are also functionally and structurally different from the novel inventive structural arrangement as set forth herein.
The present invention provides a new and novel tracking arrangement for a moving belt and particularly a flexible, woven fibrous and porous filter belt which is straightforward and economical in manufacture and assembly, eliminating or reducing many of the problems of past belt tracking arrangement, and, at the same time, requiring a minimum of parts and steps for effective operation. In addition, the present invention provides a structure and method which can be readily moved, adjusted and positioned for various types of belts, belt widths, belt fabrics and varying belt tensions, allowing for ready and easy adaptation and adjustment to various belt types, belt materials and belt sizing with ready and efficient removal and replacement of critical alignment parts as well as a proper balance of belt centering. At the same time, the novel and useful arrangement provides for straightforward and economical changing of tension in a moving belt both upon the central lineal axis of movement of a longitudinally extending belt and transverse such lineal axis of movement across the belt width.
Various other features of the present invention will become obvious to one skilled in the art upon reading the disclosure set forth herein.